I have a current Nosler & Hornady reload books. I have a recipe using a powder in Nosler that isn't listed in Hornady and vice versa. Would it be wrong to use the Nosler recipe on a Hornady Bullet or vice versa? The bullet weight is the same. I know to start out low for these loads. Just curious.

What powder bullet caliber primer case make?

Cup and core should be pretty close if not the same. I'd start at the low end and work up if using monolithic bullets with data from a cup and core bullet manufacturer. There will always be slight differences between data sources, therefore it's always good to compare.

I'd look for another source such as powder manufacturer's data.

Im with riflenut on this. Some recipes shouldn't be used.

Meh. Keep adding powder until you have to pound the bolt open with a hammer. Back off a couple grains from that load and yer GTG.

Caliber is 308 and 30:06
Primer is CCI #200
Brass is going to either be Remington, Winchester or Hornady.

Which bullet and powder do you want to use? There is over a century of load development information for the aught six, so there is a mountain of knowledge about it.

Looking at both guides, I see H4350 listed for 165 gr bullets in both. Nosler indicates a max charge of 57.5 for 2872 FPS and Hornady shows a max charge of 58.5 for 2800 FPS.

What up with this????? The same powder with the same charge should give the same velocity with 165 gr bullets, right?

NO. There are a lot of variables in play here. Different lots of the same powder or primer will have slight changes in burn rate, different brass will have changes in volume, Dave260 was working furiously at his Dillon causing the earth to wobble the day Hornady was pressure testing, etc. In reality, the 1.0 grain difference is negligible and Hornady isn't very exact in their velocities like Nosler. Personally, I wouldn't hesitate to load either bullet to 2850-2900 FPS with THIS powder, so long as I didn't experience a heavy bolt lift, but this is another subject.

Hornady lists IMR4451 but Nosler does not. Does this mean you can't use IMR4451 with Nosler bullets? NO. Reading the manufacturer description of the powder tells me it was designed to approximate the burn rate of H4350, but charge weights may be different. This tells me I can work with IMR4451 and a Nosler 165 gr BT to approximately the same velocities shown for H4350.

This is why you NEED a chronograph.

Mono metals like the Nosler E Tip or Hornady GMX, WILL have higher pressures than cup and core bullets of the same weight. Since Nosler didnt design pressure reduction rings into these bullets like a Barnes TTSX, you must start with lower powder charges.

Otherwise, there shouldn't be much difference between them but a flat base bullet will have slightly more pressure than a boattail bullet of the same weight. This is due to the longer bearing surface of a flat base bullet.

Lot of writing and I could literally write pages about this subject but .I'm going to leave for now.

The bearing surface is the key factor in pressure difference all else being the same. Hornady brass is notoriously famous for having thicker brass therefore smaller volume and therefore higher pressure.

I use multiple reloading manuals to start.never hurts to well informed.
Not every bullet or powder combo is listed that's why I educate myself with data from several sources before I start a new load
A load safe in one rifle is a primer popper in another rifle but you don't want to start to low or to high so I look at several sources